U.S. patent number 3,949,927 [Application Number 05/560,608] was granted by the patent office on 1976-04-13 for impact resistant container bottom structure.
This patent grant is currently assigned to Phillips Petroleum Company. Invention is credited to George E. MacEwen, Wayne E. Maw, Ernest L. Smith.
United States Patent |
3,949,927 |
Smith , et al. |
April 13, 1976 |
Impact resistant container bottom structure
Abstract
A container has a tubular sidewall wall member having a coating
of thermoplastic material on the inner surface thereof and a bottom
member having a coating of thermoplastic material on the upper
surface thereof. The bottom member has a central portion and a
continuous skirt extending downwardly from the periphery of the
central portion. The lower portion of the skirt is thermally bonded
to the sidewall member while the upper portion of the skirt is free
of any bond to the sidewall member. The bottom margin of the
sidewall member can be curled inwardly to form a rolled rim to
improve the impact resistance. In one embodiment the sidewall blank
can have a coating of adherence-preventing material in the area
which would be contiguous to the upper portion of the skirt. In
another embodiment the upper portion of the skirt can be coated
with an adherence-preventing material.
Inventors: |
Smith; Ernest L. (Kansas City,
MO), Maw; Wayne E. (Freeport, IL), MacEwen; George E.
(Kansas City, MO) |
Assignee: |
Phillips Petroleum Company
(Bartlesville, OK)
|
Family
ID: |
24238530 |
Appl.
No.: |
05/560,608 |
Filed: |
March 21, 1975 |
Current U.S.
Class: |
229/4.5; 220/620;
229/5.5; 229/5.84 |
Current CPC
Class: |
B65D
3/18 (20130101); B65D 3/22 (20130101) |
Current International
Class: |
B65D
3/22 (20060101); B65D 3/00 (20060101); B65D
3/18 (20060101); B65D 005/40 (); B65D 005/56 () |
Field of
Search: |
;229/5.5,4.5,14BL,21,3.1,48T,5.6,51WB ;156/289 ;428/352 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Price; William
Assistant Examiner: Garbe; Stephen P.
Claims
That which is claimed is:
1. A container having a generally upstanding tubular sidewall
member and a bottom member, the lower portion of said tubular
sidewall member forming an opening, said bottom member being
positioned within said opening formed by the lower portion of said
tubular sidewall member, said bottom member having a central
portion and a skirt, said central portion having a configuration at
least substantially conforming to the cross-sectional configuration
of the inner surface of said tubular sidewall member at the level
of said central portion, said skirt extending completely around the
periphery of said central portion and being inclined generally
downwardly from the periphery of said central portion and having a
lower portion and an upper portion, said tubular sidewall member
having a coating of a thermoplastic material on at least the inner
surface thereof, said bottom member being formed of a paper-like
fibrous material with the upper surface of said central portion and
the outer surface of said skirt contiguous to said sidewall member
having a coating thereon of a thermoplastic material, said lower
portion of said skirt and the portion of sidewall member contiguous
thereto being adhered together by a thermal bonding of the coating
of thermoplastic material on said lower portion of said skirt and
the coating of thermoplastic material on the inside surface of said
sidewall member, the coating on said outer surface of said upper
portion of said skirt being free of adherence to the coating on the
inside surface of said tubular sidewall member.
2. A container in accordance with claim 1 wherein the ratio of the
height of said lower portion of said skirt to the height of said
upper portion of said skirt is in the range of about 1:3 to about
3:1.
3. A container in accordance with claim 1 wherein said tubular
sidewall member has a bottom margin portion projecting beyond the
lower edge of said skirt, said bottom margin portion extending
inwardly and upwardly to form a rolled rim extending above the
upper edge of said lower portion of said skirt and having at least
180.degree. curvature.
4. A container in accordance with claim 3 wherein said rolled rim
extends upwardly within the opening formed by said skirt to at
least closely adjacent the lower surface of said central portion
and has at least 270.degree. curvature.
5. A container in accordance with claim 3 wherein said rolled rim
extends upwardly within the opening formed by said skirt to contact
the lower surface of said central portion.
6. A container in accordance with claim 5 wherein said rolled rim
has at least 360.degree. curvature.
7. A container in accordance with claim 6 wherein the ratio of the
height of said lower portion of said skirt to the height of said
upper portion of said skirt is in the range of 1:2 to 2:1.
8. A container in accordance with claim 7 wherein said container
has a circular cross section in a plane perpendicular to the
longitudinal axis of the container.
9. A container in accordance with claim 8 wherein at least one of
said upper portion of said skirt and the portion of said sidewall
member contiguous thereto has an outermost coating of a material
which prevents the adherence of said upper portion of said skirt to
the portion of said sidewall member contiguous thereto.
10. A container in accordance with claim 1 wherein at least one of
said upper portion of said skirt and the portion of said sidewall
member contiguous thereto has an outermost coating of a material
which prevents the adherence of said upper portion of said skirt to
the portion of said sidewall member contiguous thereto.
11. A blank for forming the bottom member of a container, said
blank being formed of a lower layer of a paper-like fibrous
material and an upper layer of thermoplastic material, said blank
having a central portion and a skirt extending completely around
the periphery of said central portion, said skirt having a first
portion and a second portion, said first portion extending
outwardly from the periphery of said central portion to said second
portion, said second portion extending outwardly from the periphery
of said first portion to the periphery of said blank, said first
portion having as the uppermost surface thereof a layer of material
which would prevent the thermal bonding of said uppermost surface
to a surface of a thermoplastic material.
12. A blank in accordance with claim 11 wherein said central
portion and said skirt meet at a first score line.
13. A blank in accordance with claim 12 wherein said blank and said
central portion have concentric circular configurations, and
further comprising a plurality of spaced score lines extending
radially outwardly from said first score line to the periphery of
said blank.
14. A blank for forming the sidewall member of a tubular container,
said blank being formed of a lower layer of a paper-like fibrous
material and an upper layer of thermoplastic material, said blank
having top and bottom edges and first and second side edges and
being adapted to be convoluted into a tubular shape with the margin
along said first side edge overlapping the margin along said second
side edge, a coating superimposed on a portion of said upper layer
of thermoplastic material in the form of a band adjacent to and
spaced from said bottom edge extending from said first side edge up
to the margin along said second side edge, said coating being a
material which would prevent the thermal bonding of said coating to
a surface of a thermoplastic material.
Description
This invention relates to packaging containers and blanks therefor.
In one aspect the invention relates to a container having an impact
resistant bottom structure. In another aspect the invention relates
to a bottom blank and/or sidewall blank for making a container with
an input resistant bottom structure.
The use of polyethylene coated paperboard for the construction of
packaging containers wherein the various components are thermally
bonded together has become extensive in recent years. However, the
polyethylene-polyethylene bond is generally stronger than the
polyethylene-paperboard bond in such containers, and any
significant impact force on the container can cause delamination of
the polyethylene coating from the paperboard in the thermally
bonded areas, thereby exposing the paperboard to the contents of
the container. Many materials which are packaged in such containers
will affect the strength of the paperboard if the paperboard is
exposed to the contents of the container, for example liquids such
as grape juice, milk, detergents, and the like.
In accordance with the present invention this problem is minimized,
if not eliminated, by bonding the lower portion of the skirt of the
botton member to the sidewall member while leaving the upper
portion of the skirt unbonded. The impact resistance of the bottom
structure can be enhanced by curling the botton margin of the
sidewall member inwardly and upwardly against the bottom
member.
Accordingly, it is an object of the invention to provide a new and
improved container. It is an object of the invention to provide a
container having an impact resistant bottom structure. Another
object of the invention is to maintain the liquid-tight integrity
of a container when the container is subjected to impact force. Yet
another object of the invention is to provide a sidewall blank for
the construction of a container having an impact resistant bottom
structure. A further object of the invention is to provide a bottom
blank for the construction of a container having an impact
resistant bottom structure. Other objects, aspects and advantages
of the invention will be apparent from a study of the
specification, the drawings and the appended claims to the
invention.
In the drawings,
FIG. 1 is a front elevational view of a container incorporating one
embodiment of the present invention;
FIG. 2 is a side elevational view of the container of FIG. 1;
FIG. 3 is a fragmentary elevational view in cross section of the
bottom structure of the container of FIG. 1;
FIG. 4 is a fragmentary elevational view corresponding to FIG. 3
after the container has been subjected to an impact force on its
bottom edge;
FIG. 5 is a fragmentary elevational view in cross section of the
bottom structure of a container incorporating another embodiment of
the invention;
FIG. 6 is a plan view of the inside surface of a sidewall blank for
making the container of FIG. 5; and
FIG. 7 is a plan view of a bottom disc blank in accordance with yet
another embodiment of the invention.
Referring now to the drawings in detail and to FIGS. 1 and 2 in
particular, the illustrated container is a generally frustoconical
container having a pinched waist configuration of the type
disclosed in E. L. Smith, U.S. Pat. No. 3,851,813, issued Dec. 3,
1974. The disclosure of U.S. Pat. No. 3,851,813 is incorporated
herein in its entirety by reference. The sidewall 7, formed of a
layer 8 of a paperlike fibrous material, such as paperboard, having
an outer coating 9 and an inner coating 10 of a suitable
thermoplastic material on the outer and inner surfaces thereof,
have been convoluted and the overlapping side margins have been
thermally bonded to each other to form a frustoconical preform
having a side seam 11. Two pinched waist forming score-line
configurations are spaced apart approximately 180.degree. on the
preform, with each comprising a first pair of score lines 12 and
13, a second pair of score lines 14 and 15, and a third pair of
score lines 16 and 17. Score lines 12 and 13 extend downwardly from
point 18 on lateral score line 19. Score lines 14 and 15 extend
upwardly and outwardly from point 21 which is spaced upwardly from
the bottom of sidewall 7. Score line 14 intersects score line 12 at
point 22, while score line 15 intersects score line 13 at point 23
to form a tetragon. Score lines 16 and 17 converge upwardly from
points 22 and 23 to intersection point 24. The folding of the
sidewall material along the score lines of the pinched waist
score-line configuration results in points 22, 22, 23 and 23 being
moved away from the longitudinal axis of the container and the
changing of the circular configurations of top edge 25 and score
line 19 into elongated configurations. The inner faces of the ridge
panels formed between score line 19 and top edge 25 are thermally
bonded together to seal the top of the container.
Referring now to FIG. 3, either before or after the sealing of the
top structure of the container, a bottom member 26 is inserted into
the open bottom end of the frustoconical preform and is thermally
bonded to the sidewall. In accordance with the present invention
the bottom member 26 is formed of a suitable paper-like fibrous
material, for example paperboard. In the embodiments of the
invention illustrated in FIG. 3, the bottom member 26 is composed
of a paperboard layer 27 having a coating 28 of a suitable
thermoplastic material on the upper face thereof and a coating 29
of a suitable thermoplastic material on the lower face thereof.
While any suitable thermoplastic material can be employed for
coatings 9, 10, 28 and 29, a normally solid polymer of at least one
monoolefin is presently preferred, with an example thereof being a
polymer of ethylene. The bottom member 26 has a central discoidal
area 31, having a diameter approximately equal to the inner
diameter of the corresponding portion of the container sidewall 7,
and an outer annular flange or skirt 32 extending continuously
around the periphery of the central discoidal area 31 and being
inclined downwardly from the periphery of the central discoidal
area 31 in general conformity to the adjacent portion of the
sidewall 7. In prior art containers wherein a flanged discoidal
bottom member is inserted into the open end of a tubular sidewall
and thermally bonded thereto, the bond is effected throughout at
least substantially the entire height of the flange. However, in
accordance with the present invention, the thermal bond of the
skirt 32 to the inner surface of sidewall 10 is effected only in
the lower portion 33 of the skirt 32, leaving the upper portion 34
of skirt 32 adjacent to but not bonded to sidewall 10. While the
ratio of the height of the lower bonded portion 33 of skirt 32 to
the height of the upper unbonded portion 34 of skirt 32 will depend
upon the size of the container, the strength of the thermal bond
required and the magnitude of the impact force for which protection
is desired, this ratio will generally be in the range of about 1:3
to about 3:1, preferably in the range of about 1:2 to about 2:1,
and more preferably in the range of about 1:1.5 to about 1.5:1.
This selective bonding of only the lower portion 33 of skirt 32 to
the sidewall 7 can be accomplished with any suitable technique. In
one embodiment a cooling means can be positioned within the opening
formed by skirt 32 and horizontally adjacent to the upper portion
34 while a heating means can be positioned horizontally adjacent to
the lower portion 33, thereby permitting the temperature of the
thermoplastic coating 28 on the lower portion 33 of skirt 32 to be
raised to a thermal bonding temperature while the temperature of
the thermoplastic coating 28 on the upper portion 34 of skirt 32 is
maintained below the minimum thermal bonding temperature. In
another embodiment illustrated in FIGS. 5 and 6, a layer 36 of
adherence-preventing material is applied as the outermost layer
over the thermoplastic coating 10 on the inside surface of sidewall
7 throughout the area which is to be in contact with the upper
portion 34 of flange 33. Thus, the layer 36 extends from one side
edge 37 of the sidewall blank to the other side edge 38 of the
sidewall blank except for the side margin 39 which is overlapped in
the formation of the side seam 11. The layer 36 extends upwardly
from the upper edge of the bottom portion 33 to at least level
with, and preferably higher than the upper surface of the central
discoidal portion 31 of bottom member 26, to prevent any thermal
bonding of upper portion 34 to the sidewall 7. In another
embodiment an annular layer 41 of adherence-preventing material is
applied to the bottom member 26 as the uppermost layer in upper
portion 34, as shown in FIG. 7. The bottom member 26 and the
central discoidal area 31 can have concentric circular
configurations. The bottom member 26 can be provided with an
annular score line 42 defining the junction between the central
discoidal area 31 and skirt 32. A series of score lines 43 can
extend radially outwardly from score line 42 to the periphery of
bottom member 26 to promote uniformity in the folds formed in skirt
32 when the bottom member 26 is bent along score line 42 to cause
skirt 32 to extend downwardly from the peripheral edge of central
discoidal area 31. The layer 41 extends outwardly from the
periphery of central discoidal area 31 defined by groove 42 to the
line of demarkation between lower portion 33 and upper portion 34
of skirt 32. The adherence-preventing material can be any suitable
material which can be coated onto the thermoplastic coating 10 of
sidewall 17 or the thermoplastic coating 28 of bottom member 26 and
which will subsequently prevent thermal bonding with the
thermoplastic coating 28 or 10, respectively. Examples of suitable
adherence-preventing coating materials include, but are not limited
to, cellophane; metal foils; and thermosetting resins, such as heat
resistant latex water varnish, catalyzed epoxy material,
fluorocarbon material, and various nitrocellulose materials
formulated from a base nitrocellulose resin and a plasticizer.
Referring now to FIG. 4, the container of FIGS. 1-3 has been
subjected to an impact force on the bottom edge of the container by
the container having been dropped onto the floor. The weight of the
contents of the container caused the deformation of bottom member
26 upon impact, by forcing the central discoidal area 31
downwardly, bending the upper portion 34 of skirt 32 inwardly away
from the sidewall 7. However, the liquid-tight seal between the
lower portion 33 of skirt 32 and sidewall 7 remains intact. As a
result of upper portion 34 of skirt 32 not being bonded to the
sidewall 7, there was no delamination of thermoplastic coating 10
from paperboard 8 and/or delamination of thermoplastic coating 28
from paperboard 27 which would have occurred if upper portion 34
had been thermally bonded to sidewall 7. Such delamination would
have exposed the paperboard to the contents of the container,
substantially reducing the serviceability of the container for
packaging any material which would adversely affect the
paperboard.
In the presently preferred embodiments of the invention, the bottom
margin 46 of sidewall 7, which is the portion of sidewall 7
extending beyond the lower edge of skirt 32, is rolled inwardly and
upwardly to form a rolled rim extending above the upper edge of
bottom portion 33 and preferably at least closely adjacent, and
more preferably in contact with, the lower surface of central
discoidal area 31. This rolled rim serves as a shock absorber for
the central discoidal area 31, minimizing the effects of the impact
on central discoidal area 31. The rolled rim has at least
180.degree., preferably at least 270.degree. and more preferably at
least 360.degree., of curvature.
While the invention has been described in terms of a frustoconical
container having a larger base than top, the invention is also
applicable to other types of containers having an at least
generally upstanding tubular sidewall member, including cylindrical
containers, containers having an oval cross section in a plane
perpendicular to the longitudinal axis of the container,
frustoconical containers having a larger top than base, rectangular
containers, containers with a base of at least five sides, etc. In
each such container the bottom member will be positioned in the
opening formed by the lower portion of the tubular sidewall member,
and the central portion of the bottom member will have a
configuration at least substantially conforming to the
cross-sectional configuration of the inner surface of the tubular
sidewall member at the level of the central portion of the bottom
member. When it is desirable to employ the rolled rim 46 on a
container which has a polygonal base, the portion of the sidewall 7
below the bottom edge of skirt 32 can be notched to form tabs which
correspond in length and location to the polygonal base, and these
tabs can then be curled inwardly and upwardly to form the rolled
rim 46 without interference from each other at the corners of the
base. The container sidewall member and/or the bottom member can be
provided with additional coatings between the layer of paper-like
fibrous material and the layer of thermoplastic material utilized
to effect the heat seal. For example either or both of these
members can be lined with a metal foil, such as aluminum foil.
Other reasonable variations and modifications are possible within
the scope of the foregoing disclosure, the drawings and the
appended claims to the invention.
* * * * *